Recent biochemical and genetic evidence has shown that carbohydrate binding protein (CBP-26) is intimately involved in the cell-cell cohesion process. We have isolated the cell surface associated receptor molecule for CBP-26 by lactoperoxidase-catalysed radioiodination followed by isolation by CBP-sepharose 4B chromatography. The receptor has a molecular weight of 80,000 daltons. The CBP receptor is constitutively expressed during development. Most significantly, the receptor, when added to aggregation-competent cells, blocks the cells' ability to reaggregate. These results suggest that CBP and its receptor play a very important role in cell cohesion and aggregation process.